1. Field of the Invention
The invention relates to a display device. More particularly, the invention relates to a display device having a color filter layer and a method for manufacturing the display device.
2. Description of Related Art
The performance of a display device is often subject to a fringe field effect (FFE). Specifically, when the density of sub-pixels is high, or the distance between two adjacent sub-pixels is close, the FFE needs to be taken into consideration. In an exemplary liquid crystal on silicon (LCOS) display device, the density of the sub-pixels is high, and the distance between the adjacent sub-pixels is short. Hence, the FFE on the sub-pixels results in light leakage between the adjacent sub-pixels. FIG. 1A is a schematic partial top view illustrating a sub-pixel array in a conventional display device 100. FIG. 1B is a schematic explosive view illustrating the sub-pixel array depicted in FIG. 1A. With reference to FIG. 1A and FIG. 1B, the display device 100 includes a color filter layer 110, a sub-pixel electrode layer 120, a liquid crystal layer 130, a transparent electrode layer 140, and a substrate 150. The electrode layers 120 and 140 are configured on the substrate 150. The liquid crystal layer 130 is configured between the electrode layers 120 and 140. The color filter layer 110 is configured between the sub-pixel electrode layers 120 and the liquid crystal layer 130.
The material of the transparent electrode layer 140 is any transparent conductive material, e.g., indium-tin oxide (ITO). The sub-pixel electrode layer 120 has a plurality of sub-pixel electrodes (e.g., sub-pixel electrodes 121, 122, and 123). The conventional color filter layer 110 has a plurality of color areas (e.g., color areas 111, 112, and 113). The shape and the location of the color areas in the conventional color filter layer 110 are the same as the shape and the location of the corresponding sub-pixel electrodes in the sub-pixel electrode layer 120. For instance, the color area 112 and the sub-pixel electrode 122 are rectangular, and the color area 112 merely covers the sub-pixel electrode 122. The color area 112 does not cover the sub-pixel electrodes (e.g., the sub-pixel electrodes 121 and 123) adjacent to the sub-pixel electrode 122.
The electric field between the sub-pixel electrode 122 and the transparent electrode layer 140 can drive the corresponding liquid crystal in a region on the liquid crystal layer 130, so as to change the light transmission rate of the corresponding region containing liquid crystal. Theoretically, the ideal electric field between the sub-pixel electrode 122 and the transparent electrode layer 140 affects the liquid crystal in the region where the sub-pixel electrode 122 is located (i.e., the region where the color area 112 is located) but does not affect the liquid crystal in the region (hereinafter “liquid crystal region”) where the adjacent sub-pixel electrodes (e.g., the sub-pixel electrodes 121 and 123) are located. However, practically speaking, the range of the fringe field distribution (i.e., the range of the electric field distribution) of the sub-pixel electrode 122 in the sub-pixel array is overlapped with the liquid crystal region where the adjacent sub-pixel electrodes are located. For instance, the fringe field distribution range of the sub-pixel electrode 122 is represented by a dotted line 10 in FIG. 1A. A partial area 11 within the fringe field distribution range 10 is overlapped with the liquid crystal region where the adjacent sub-pixel electrode 121 is located, and another partial area 13 within the fringe field distribution range 10 is overlapped with the liquid crystal region where the adjacent sub-pixel electrode 123 is located. This is the so-called FFE.
It is assumed that the color areas 111, 112, and 113 are red, green, and blue areas. The fringe field distribution range 10 shown in FIG. 1A allows the sub-pixel in the color area 112 to display green light; the partial area 11 within the fringe field distribution range 10 may have red light leakage at the color area 111; the partial area 13 within the fringe field distribution range 10 may have blue light leakage at the color area 113. Apparently, the FFE on the sub-pixels leads to unexpected color light leakage, which is detrimental to the display performance of the display device 100.
FIG. 2 is a schematic partial top view illustrating a sub-pixel array in a conventional display device 200. The description of the display device 200 in FIG. 2 can be referred to as the description of the display device 100 in FIG. 1. The difference between the display device 100 and the display device 200 lies in that the area of the sub-pixel electrodes in the display device 200 is reduced. For instance, the upper-right and lower-left corners of the sub-pixel electrode 122 are cut, as indicated in FIG. 2. Thereby, the fringe field distribution range of the sub-pixel electrode 122 can be modified, such that the modified fringe field distribution range of the sub-pixel electrode 122 conforms to the shape of the color area 112. As such, the conventional issue of FFE has been resolved. Nonetheless, the reduction of the area of the sub-pixel electrode leads to the decrease in both the aperture ratio of the sub-pixel and the maximum display brightness of the display device 100.